For those who like their wildlife tame, BBC2’s new series Orangutan Diary is a tellyfest of sentimentalised furriness. There’s Nobby, the “bad boy” of the nursery class who is graduating to “forest school” where a team of teachers will teach him how to live in the wild. There are the “irresistible orphans” Peanut and Pickles. In fact, the entire cast sounds as if it has come from a five year-old’s soft toy box. It helps that in the cuteness stakes, orangutans are at the top of the evolutionary tree.

The mancubs come in the form of presenters Steve Leonard, the television vet, and Michaela Strachan. But the strangest creature in the cast has to be David Irons, a 46-year-old doctor who, when he isn’t tending to the apes in the Borneo Orangutan Survival Foundation’s (BOS) centre at Nyaru Menteng, is patching up Scots in the accident and emergency department of the Galloway Community Hospital in Stranraer. For those who believe wildlife is in danger of becoming Disneyfied to an unnatural degree, Irons, who gives a whole new meaning to the term going ape, represents the ultimate in anthropomorphism.

The GP, who also tutors seafarers in medicine for the Maritime and Coastguard Agency, is an accidental pioneer in the medical treatment of great apes. He has crossed the species barrier and is now using the skills he has developed in the NHS to save orangutans under threat from poachers and the loss of their habitat to palm oil plantations. Irons believes the medical diagnosis and treatment of animals and humans is part of a continuum and that doctors are better placed than vets to treat great apes.

“Orangutans have 97% of their DNA in common with us, their anatomy is very similar and their systems work, in most cases, practically the same as ours,” he says, speaking from Borneo. “They are prone to the same diseases as we are and respond to similar treatments. Where great apes are concerned, there is a significant overlap between veterinary and human medicine.”

It’s a controversial view, particularly in a Muslim country where medical resources for humans are scarce, as Irons knows only too well. Last October he fell dangerously sick and ended up battling failing consciousness to self-administer a treatment that almost certainly saved his life.

“When something happens, it feels very remote here,” he says. “It is scary when you realise there is nobody else to rely on. My illness came on very suddenly. I was well in the morning. I felt a bit light-headed at lunchtime. Four hours later I was starting to become uncoordinated. I couldn’t stay upright on my bicycle.

“By the time I got home I was hallucinating and losing it very rapidly. I was developing sceptic shock and I couldn’t get through to anyone on the phone. I had to give myself an intramuscular injection of antibiotics. I work in an emergency department and I don’t usually panic but when you are rapidly losing consciousness, which was what was happening to me, it is frightening.”

The BOS centre, founded 19 years ago by an extraordinary Danish naturalist, Lone Dröscher-Nielson, is far from the jungle paradise BBC viewers might believe. Dröscher-Nielsen, who gave up a career as an air hostess to work with the orangutans and has run it almost single-handedly for years, originally built the sanctuary to take 150 orphaned or maltreated apes. There are now about 700, and up to 20 animals arrive every month. It costs $1.5m (£1.05m) a year to keep the place going.

“It’s an amazing sight to see a couple of hundred orangutans just playing together as if they were in a school playing field,” says Irons. “It is very uplifting. At the same time you know they are here because their mothers have been hacked to death. It's a bittersweet experience. You can’t help your heart going out to them but you also wish they weren’t here because of how they got here. It is a wonderful experience in many ways but when you see what Lone has been through in the past 15 years you realise it is not a paradise. It can be very stressful. There are real ups and downs. It is daunting.”

Irons who has previously volunteered in Argentina, working with disadvantaged children, and in Thailand working with animals, ended up at BOS almost by chance. Two years ago he saw a BOS appeal for £3,000 to help rehabilitate 15 orang-utans rescued from kick-boxing tournaments in Thailand. He knew that if he worked medical shifts over Christmas and New Year, he could raise the money.

“It’s a little bit clichéd but I felt I had to put something back into the equation,” he says.

He raised the money and also offered his services as a volunteer, not expecting to hear anything more. Then an invitation arrived to a BOS fundraiser in London, but because Irons had moved house, he did not receive it until the day before the event. He managed to get there and met Dröscher-Nielsen. They hit it off and she decided she could use his help, although initially Irons, who arrived 18 months ago, had no plans to treat the apes medically.

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